function sub(){
    var preson = document.querySelector(".author").value;
    var content = document.querySelector(".comment-content").value;
    var presonNode = document.createTextNode(preson);
    var contentNode = document.createTextNode(content);
    // 创建文本内容
    var tdPreson = document.createElement("td");
    var tdContent = document.createElement("td");
    var tr = document.createElement("tr");
    // 创建标签
    tdPreson.appendChild(presonNode);
    tdContent.appendChild(contentNode);
    tr.appendChild(tdPreson);
    tr.appendChild(tdContent);
    document.querySelector(".title").appendChild(tr);
    preson="";
    content="";
}
